Things have been going pretty well lately for the National Football League. Revenues this past year were about $10 billion. Arguably, football is the most watched and followed sport in this country.

But developments surrounding a new football stadium for the Minnesota Vikings offer a glimpse of an emerging, unseemly indifference by the team's owners and the NFL to wildlife impacts that is disturbing to millions of people who care about the nonhuman species that share our planet.

Plans for the proposed stadium call for a massive wall of glass, which experts say will assuredly kill thousands of birds over the life of the facility. Bird and wildlife advocates have raised this concern with stadium developers and with city planners. Reasonable solutions were offered from conservationists early in the process.

The response from the team and the NFL has been as frigid as the Minnesota winters: the glass will go in exactly as planned. And this is in spite of a new resolution from the Minneapolis City Council calling for bird-saving preventative measures.

The stadium, which is expected to open in two years, will cost almost $1 billion to build. The bird-friendly changes requested — installing "fritted" glass with ceramic dots that birds see and generally avoid — would cost about $1.1 million. For an outlay of one-tenth of 1 percent of the cost of the stadium, this problem goes away. This is pocket change to the NFL and team owners.

For some reason, team owners and the NFL feel empowered to ignore what in all likelihood will be daily avian carnage at their facility. The irony of that position is stunning: The NFL makes massive marketing use of birds such as eagles (Philadelphia), falcons (Atlanta), cardinals (Arizona), seahawks (Seattle) and ravens (Baltimore) while at the same time sanctioning the building of stadiums with features that serve as bird death traps.

How big a problem is bird collisions with glass? Huge.

A recent report from federal scientists at the Smithsonian Institution and the U.S. Fish and Wildlife Service revealed bird-glass collisions are the second-leading human-caused mortality threat faced by birds, with between 400 million and 1 billion birds killed in the U.S. in that fashion every year. All kinds of birds are affected: hawks, falcons, owls, songbirds. It is one reason why over 200 species of birds are in decline or otherwise in serious trouble.

Team owners and the NFL would do well to recognize that Minneapolis is one of a relative handful of cities that have the laudable distinction of being federally designated as an Urban Bird Treaty city, which means that they have shown uncommon interest in protecting and conserving birds. Somehow, I think some have forgotten what that means— and how inconsistent current actions are with that notable designation.

I hope the NFL will step in and demonstrate some level of common sense and compassion for wildlife, encouraging the Minnesota Vikings (and other team owners with similar problems) to do the right thing. Absent that, about 100,000 Viking football fans will be exposed to a lot of "inconvenient truths" each game: the repeated thud as birds crash into a glass wall at 40 mph, and the sight of birds littering the ground.

This is the opinion of George Fenwick, president of the American Bird Conservancy in Washington, D.C. A version of this commentary was distributed to media statewide.